As high-frequency radio communication technology advances, there has been an increasing demand for high performance, compact size, and low cost amplifiers. It is a common practice to add a feedback network to the amplifier to improve its characteristics over process, supply voltage, and temperature (PVT).
Typically, the feedback network is coupled between a signal input and a signal output of the amplifier to form an amplification system. The feedback network is configured to enhance gain flatness, return loss, and out of band (low and high frequency) stability of the amplification system without disturbing the DC bias conditions on the input stage. However, a relatively large resistance and/or capacitance of the feedback network may significantly increase the turn-on time of the amplification system, which may not be acceptable in some applications. In addition, inductor usage in the amplification system may be limited, because it may be difficult to achieve a high-Q inductance in the band of interest, or cost/die size becomes a dominating factor in the amplification system.
Accordingly, there remains a need for improved amplification system designs, which reduce the turn-on time while performing correctly under process, supply voltage, and temperature variations. In addition, the amplification system designs will preferably be low cost and compact, and the circuitry of the amplification system will retain its simplicity.